The HA-1A MK3 adds selectable impedance matching and tube preamplifier output

The Cayin HA-1A MK3 is a compact Class-A tube headphone amplifier and preamplifier built around two JJ 12AU7/ECC82 tubes and two Electro-Harmonix EL84EH/6BQ5 output tubes. Dedicated power and output transformers support its fully analog signal path, while selectable headphone impedance matching accommodates loads from 8 to 600 ohms. With 6.35 mm and 4-pin XLR headphone outputs, two RCA inputs, and a dedicated RCA preamplifier output, the HA-1A MK3 is designed for desktop systems that need to accommodate both headphone and speaker-based listening.

12AU7 and EL84 tube amplification

The HA-1A MK3 uses two JJ 12AU7/ECC82 tubes alongside a pair of Electro-Harmonix EL84EH/6BQ5 tubes. The amplifier operates entirely in the analog domain, with the tube complement forming the basis of Cayin's dedicated amplification circuit rather than supplementing a separate solid-state signal stage.

The output stage runs in Class A, keeping its active devices conducting throughout the signal cycle. This operating method favors continuous, linear amplification at the expense of electrical efficiency and is consistent with Cayin's approach to compact dedicated tube headphone amplifiers.

Dedicated power and output transformers

Cayin developed dedicated power and output transformers specifically for the HA-1A MK3. The power transformer supports the amplifier's supply requirements, while the output transformers provide the interface between the tube output stage and connected headphones.

Separate power-supply sections and the amplifier's internal component arrangement are intended to provide a stable electrical foundation while limiting unwanted interaction between sections of the circuit. An ALPS volume potentiometer handles level adjustment, joining the custom transformers and tube circuitry within the compact chassis.

Impedance matching from 8 to 600 ohms

A two-position impedance selector changes the HA-1A MK3's headphone matching for different load requirements. The Low setting covers headphones rated from 8 to 150 ohms, while the High setting covers 151 to 600 ohms.

This gives the output stage dedicated operating ranges for lower-impedance planar magnetic headphones as well as higher-impedance dynamic designs. Rather than relying on a single output configuration across the full impedance range, users can select the transformer matching appropriate for the connected headphone.

6.35 mm and 4-pin XLR headphone outputs

The front panel provides both 6.35 mm single-ended and 4-pin XLR headphone connections. Cayin rates the 6.35 mm output at 2,400 mW + 2,400 mW, while the 4-pin XLR connection is rated at up to 2,700 mW + 2,700 mW.

The two output formats allow the HA-1A MK3 to accommodate common headphone cable terminations without requiring an external adapter. Combined with the selectable impedance ranges, they broaden compatibility across headphones with substantially different electrical requirements and connection standards.

Tube preamplifier operation

A rear-panel RCA PRE-OUT allows the HA-1A MK3 to operate as a tube preamplifier for active loudspeakers or a separate power amplifier. Two pairs of RCA analog inputs provide source switching for connected components, allowing the same amplifier and volume control to serve both headphone and loudspeaker playback chains.

Cayin combines the tube circuit, dedicated transformers, separate power-supply sections, and ALPS potentiometer with hand assembly and inspection as part of its established tube-amplifier manufacturing process.

Availability

The Cayin HA-1A MK3 is available now on Apos.